1. Field of the Invention
The present invention relates to a straight-type metal spoke for a cycle wheel. The invention also relates to a wheel equipped with such spokes.
The invention also relates to a method for making such a metal spoke for a cycle wheel, as well as a method for making a wheel having such spokes.
2. Description of Background and Relevant Information
Current commercially available metal spokes are made of stainless steel or zinc-coated steel. Such spokes have an elongated spoke body, with a head at one of the ends. In spokes of the straight type, the head is in the direct extension of the tapered body. The other end of the spoke is threaded, and it is provided to engage into a spoke nipple.
One of the main mechanical properties of a spoke is its elastic resistance and tractional rigidity. Another characteristic is its fatigue strength. Further, reference can be made to the weight that influences the inertia of the wheel, and the penetration into the air.
To improve the elastic resistance of the spoke, it is common to use a worked-hardened stainless steel. However, this has a disadvantage in that the shaping of the spoke is not carried out under good conditions. This shaping consists of forming the head, and if necessary, of flattening the filament to improve its penetration into the air. Indeed, because of the work hardening, only small sized heads can be obtained, which therefore have a limited bearing. This induces zones of very high stresses in the fastening zones, especially on the hub. Furthermore, their fatigue strength is not very good because of hairline cracks that may occur during shaping of the spoke.
Another disadvantage of the current spokes is that the spoke nipple which is used for fastening the spoke on the side of the rim is an independent element. Thus, the mounting of a spoke requires handling of two separate elements which must be presented on the rim from two different sides.